Packet communicating apparatus

ABSTRACT

Bandwidth control over users accommodated under ONU in PON is achieved. BAS sets user bandwidth information obtained during user authorization in OLT. The OLT achieves bandwidth control on a user basis, using bandwidth information set from the BAS. The present invention enables bandwidth control over users under the ONUs.

FIELD OF THE INVENTION

The present invention relates to a packet communicating apparatus andmore particularly to a bandwidth control method in PON (Passive OpticalNetwork).

BACKGROUND OF THE INVENTION

In recent years, faster access networks have been developing rapidly,and FTTH (Fiber To The Home) using optical fibers has been coming intowidespread use. Optical fiber installation configurations for achievingFTTH fall into three broad categories: (1) SS (Single Star) typenetworks in which the station of a common carrier and users areconnected by an optical fiber with a one-to-one correspondence; (2) ADS(Active Double Star) type networks in which an active element RT (RemoteTerminal) for multiplexing and separating signals and transformingsignals electrically and optically is installed between a common carrierand users so that the common carrier and the RT are connected by anoptical fiber, and the RT and users are connected by a metal cable witha one-to-one correspondence; and (3) PDS (Passive Double Star) typenetworks (global standard name PON: Passive Optical Network) in which alight splitter SC (Star Coupler) is installed between a common carrierand users, a light signal from the station is branched in the SC, andoptical fibers are installed between the SC and the users.

The PON type networks are lower in fiber installation cost than the SStype networks in which all users and the station are connected with eachother by an optical fiber with a one-to-one correspondence. Also, the SCfor branching light is a highly reliable passive element and requires noelectrical supply, therefore not requiring a power facility andprovision for power failure. For these reasons, the PON type networksare very promising technology for achieving FTTH.

Referring to FIG. 1, a description is made of BPON (Broadband opticalaccess systems based on Passive Optical Network), which is PON using ATM(Asynchronous Transfer Mode). The BPON comprises an optical linetermination (OLT) 10, optical network units (ONU) 12, and an opticalstar coupler (SC) 11 (hereinafter, a PON configuration including OLT,SC, and ONU will be referred to as a PON system). The OLT 10, which isprimarily installed in a building or the like of a common carrier, makesauthorization and bandwidth management for the ONUs 12 in the PONsystem. The ONUs 12 terminating a user network transform user packetsreceived from users to ATM cells and output as many ATM cells asspecified time slots at a timing specified by the OLT 10. The SC 11,which is a passive element constructed of an optical fiber, branches anoptical fiber 16 of the OLT side to plural optical fibers 17-1, 17-2, .. . , and 17-n of the ONU side. User data sent from the OLT 10 are sentto all ONUs via the SC 11. The SC 11 multiplexes upstream user packetsdelivered from the ONUs 12 and outputs the multiplexed packets to theOLT 10. Time slot assignment to the ONUs is made by an OpS (OperationSystem) 14 connected to the OLT 10. The interface between the OpS 14 andthe OLT 10 is defined by ITU-TQ.834.1. Here, the direction from the OLTto the ONUs is defined as downstream. The direction from the ONUs to theOLT is defined as upstream.

FIG. 4 shows a frame format in BPON. FIG. 4 shows, beginning at the top,a downstream frame format, an upstream frame format, and an enlargedportion of the upstream frame format. The OLT 10 sends 224 downstreamATM cells to the ONUs in one cycle, and sends a PLOAM (physical layerOAM) cell 241 to the ONUs 12 every 27 cells for the purpose of systemcontrol and the setting of upstream bandwidths. The ONUs 12 monitorconnection identifiers VPI/VCI contained in cell headers of ATM cells252 received from the OLT 10, get only cells directed to the pertinentONUs 12, and send user data to physical lines 18 of the user side. TheONUs 12 transform user packets received from users 13 to ATM cells,append a header PON-OH (PON-OverHead) 251 to the leading portion of theATM cells, and output the ATM cells to the OLT 10. The timing in whichthe ONUs 12 output the cells and the number of time slots are set in thesystem control cell PLOAM 241 sent from the OLT 10 and thereby specifiedto the ONUs by the OLT. Upstream cells sent to the OLT from the ONUs aremultiplexed (e.g., time division multiplexing) on an identical opticalfiber of the OLT side in the SC. To prevent cells sent from the ONUsfrom conflicting with each other in the SC, the OLT uses the PLOAM cellto make output timing adjustment called ranging and set timing in theONUs. The OLT assigns time slots to the ONUs. In other words, time slotassignment in consideration of users under the ONUs is not performed.

A transfer method of a BPON system is defined by ITU-T G.983.1 andG.983.2. For EPON (Ethernet-PON) systems that perform a transfer betweenOLT and ONUs over Ethernet, IEEE 802.3ah is pushing ahead withstandardization of transfer methods.

FIG. 6 shows a network configuration that allows users to connect to theInternet 30 in FTTH. This network comprises a broadband access serverBAS 28 that performs aggregation of user accesses, user management, andservice allocation; an OLT 10 that receives user data from the BAS andsends it to a PON system, and manages the PON system; SC 11 thatbranches a single optical fiber to plural optical fibers; and ONUs 12that terminate user access and send user data to the PON system (OLT)according to the OLT. Users 13 are authorized in the BAS via the ONUs 12and the OLT 10 before being connected to the Internet. In thisconfiguration, the PON system is used as a communication path forconnecting the ONUs installed within user premises and the BAS, whereina bandwidth has been allocated to the communication path.

In BPON and EPON systems, a path between ONUs and OLT is used as a datapath to which a bandwidth has been allocated, and bandwidth controlbetween OLT and ONUs is performed in an ONU unit. As more and more usersintroduce FTTH, a PON system suffers from the problem of the number ofbranches of SC. Since one ONU is normally installed for each user, anoptical fiber of one branch is required for one user. To accommodatemore users in an identical PON system, the SC must be adapted to havemore branches. The number of branches of the SC is limited by physicalconstraints attributed to laser output installed in both the OLT andONU. Multiple branches are achieved only by use of very expensive andhigh-output lasers. Accordingly, one method for avoiding the limitationon the number of branches is to accommodate plural users in an ONU andshare the ONU among the users. However, since the OLT and the BASoperate independently, in the prior art, the OLT has not performedbandwidth control for each of users under the ONUs.

SUMMARY OF THE INVENTION

The present invention aims at performing bandwidth control on a userbasis between OLT and ONUs.

To achieve the above object, the present invention performs bandwidthcontrol under cooperation between the BAS and OLT. Bandwidth informationallocated to each user is registered in advance in a RADIUS server andused for bandwidth setting during user authorization. The BAS uses auser profile obtained during the authorization to perform bandwidthcontrol of the PON system. PPP is used for authorization between usersand the BAS, and bandwidth control is achieved by passing bandwidthinformation of each user obtained from the RADIUS server to the OLT. TheOLT uses session ID of PPPoE to identify user data. This is created whena session between the BAS and a user is established. User packets arebuffered and shaped every session ID to achieve bandwidth control on auser basis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a network configuration of a general PONsystem of the prior art;

FIG. 2 is a diagram showing the configuration of OLT used in FIG. 1;

FIG. 3 is a diagram showing the configuration of ONU used in FIG. 1;

FIG. 4 is a diagram showing upstream and downstream frame formats inBPON of the prior art;

FIG. 5 is a diagram showing a PPPoE frame format;

FIG. 6 is a diagram showing the configuration of a network in which thegeneral PON in FIG. 1 and BAS are connected;

FIG. 7 is a diagram showing the configuration of the BAS used in FIG. 6;

FIG. 8 is a diagram showing a network configuration in which BAS and OLToperate in cooperation and the BAS performs system control through aseparate line;

FIG. 9 is a diagram showing the configuration of the BAS in FIG. 8;

FIG. 10 is a diagram showing the configuration of a PON interfaceinstalled in OLT in a bandwidth control method on an ONU basis;

FIG. 11 is a diagram showing an ONU bandwidth control table provided inFIG. 10;

FIG. 12 is a diagram showing the configuration of a PON interfaceinstalled in OLT in a bandwidth control method on a user basis;

FIG. 13 is a diagram showing a user bandwidth control table provided inFIG. 12;

FIG. 14 is a diagram showing the configuration of a line control unithaving an interface conforming to Q.983.1 for OLT control in the methodof FIG. 8 for performing bandwidth control by a special line from BASunder cooperation between the BAS and OLT;

FIG. 15 is a diagram showing a network configuration in which BAS issuesOLT control packets by in-channel communication, in OLT bandwidthcontrol from BAS under cooperation between the BAS and OLT;

FIG. 16 is a diagram showing the configuration of BAS used in theconfiguration of FIG. 15 for in-channel communication from the BAS toOLT;

FIG. 17 is a diagram showing the configuration of OLT in theconfiguration of FIG. 15 for OLT system control by in-channelcommunication from BAS;

FIG. 18 is a diagram showing a network configuration in which OLT isaccommodated in BAS as a line interface and used integrally with theBAS;

FIG. 19 is a diagram showing the configuration of BAS in FIG. 18 inwhich OLT is accommodated as a line interface and used integrally withthe BAS;

FIG. 20 is a diagram showing the configuration of an OLT interface inFIG. 19 showing the configuration of BAS in which OLT is accommodated asa line interface and used integrally with the BAS;

FIG. 21 is a diagram showing the configuration of a packet processingunit in FIG. 19 showing the configuration of BAS in which OLT isaccommodated as a line interface and used integrally with the BAS;

FIG. 22 is a diagram showing bandwidth allocation sequences among BAS,OLT, and ONU in a method of controlling bandwidths allocated to ONUsaccording to the number of users accommodated under the ONUs and userbandwidths;

FIG. 23 is a diagram showing a flow of control by BAS in a method ofcontrolling bandwidths allocated to ONUs according to the number ofusers accommodated under the ONUs and user bandwidths;

FIG. 24 is a diagram showing system control sequences among BAS, OLT,and ONU in a method of performing bandwidth control for each of usersaccommodated under ONUs;

FIG. 25 is a diagram showing PPPoE and PPP sequences exchanged amongBAS, OLT, and users in FIG. 24;

FIG. 26 is a diagram showing a flow of control by BAS in a method ofperforming bandwidth control for each of users accommodated under ONUs;and

FIG. 27 is a diagram showing an example of the setting of userattributes set in a RADIUS server.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to the accompanying drawings.

FIG. 8 shows a network configuration in which BAS and OLT operate incooperation and the BAS performs system control through a separate line.The network system in FIG. 8 comprises BAS 28, OLT 10, and ONU 12,wherein the BAS and the OLT operate in cooperation in such a way thatthe BAS, during user authorization, passes user bandwidth informationobtained from a RADIUS server to the OLT to perform bandwidth control ona user basis under the ONU.

FIG. 9 is a functional block diagram of the BAS used in FIG. 8. The BAScomprises: an input side line control unit 283; output side line controlunits 400; an input side packet processing unit 284; output side packetprocessing units 286; a switch 285; a system control unit 281; and anOpS interface 282 used for control from a management terminal. Uponreceipt of a packet from the outside, the input side line control unit283 performs physical layer processing and transfers the packet to thepacket processing unit 284. The input side packet processing unit 284performs protocol processing such as PPP termination and transfer in theIP layer for the packet received from the line control unit 283, andtransfers the packet to the switch 285. The switch 285 performsswitching to a path decided in the packet processing unit 284 andoutputs the packet to a corresponding output side packet processing unit286. The output side packet processing unit 286 performs protocolprocessing such as L2TP of layers 2 and 3 to match an output side line,and outputs the packet to the line control unit 400. The line controlunit 400 performs physical layer processing and outputs the packet tothe OLT 10. The BAS in FIG. 7 is different from that in FIG. 6 in thatan interface for OLT control is added to the line control unit.

FIG. 2 is a functional block diagram of the OLT used in FIG. 8. The OLTcomprises: a line control unit 100; a switch 104; PON interfaces 105; asystem control unit 102; and an OpS interface 101. Data received fromthe BAS 28 is outputted to the switch 104 after the line control unit100 terminates the physical layer and decides a path. The switch 104outputs the packet to a PON interface 105 corresponding to a pathdecided by the line control unit 100. The PON interface 105 performs PONsystem management such as bandwidth setting between OLT 10 and ONUs 12,output timing management, and authorization between OLT 10 and ONUs 12,and sends and receives data to and from the ONUs 12. Managementinformation of the PON system is set in the PON interfaces 105 from anexternal terminal through the OpS interface 19. The PON interfaces 105use the setting information to control downstream bandwidth from the OLT10 and control upstream bandwidth to the OLT 10 from the ONUs 12 bysending a management packet to the ONUs 12. Upon receipt of the packetfrom the output side packet processing unit, the PON interface 105buffers it in an ONU 12 of an output destination and outputs data to theoptical fiber 16 with a bandwidth allocated to the ONU 12.

FIG. 3 is a functional block diagram of the ONU used in FIG. 8. The ONUcomprises: a system control unit 121; a PON interface 122; and a linecontrol unit 123. The PON interface 122 extracts only packet directed tothat ONU from data sent from the OLT 10 and transfers the packet to theline control unit. Also, the PON interface 122 performs upstreambandwidth control and sending timing control on the basis of controlinformation sent from the OLT 10.

In the network configuration shown in FIG. 6, the PON operatesindependently of the BAS 18 and is used as a data path for connectingthe BAS 18 and a user network 13 under the ONU, wherein a bandwidth isallocated to the data path. Bandwidths between the OLT 10 and ONU 12 areset in an ONU basis by OpS 14-1 of the OLT 10.

In this embodiment, the BAS and OLT operate in cooperation, andbandwidth control is achieved on a user basis by reflecting userinformation obtained by BAS user authorization in the OLT. Hereinafter,an embodiment of EPON will be described.

In this embodiment, PPP is used for user authorization and Ethernet isused for physical lines for connecting the ONUs and user terminals. Userinterfaces are not limited to Ethernet. In cases where physical linesare Ethernet, packets are transferred over PPPoE. The PPPoE is definedin RFC2516 and its packet format is as shown in FIG. 5. In thisembodiment, the OLT has a bridge function and the ONUs have a routerfunction. That is, the PON interface 122 of the ONUs, which has MACaddresses, changes a sender MAC address specified by a user to a MACaddress of the PON interface and a destination MAC address to a MACaddress of the line control unit 287 of the BAS and sends them to theBAS. The OLT sends MAC addresses of the ONUs to the BAS withoutmodification. The OLT or ONU can include either of the bridge functionand the router function. The ONUs monitor destination MAC addresses ofpackets outputted by the OLT and capture packets directed to thepertinent ONUs. The BAS consults the RADIUS (Remote AuthorizationDial-In User Service) server 26 about user information during userauthorization, and obtains authorization and user information for user'snetwork settings. Since RFC2138 defining the RADIUS server is notsupposed to be used in PON, attributes for parameters used for PONbandwidth control are not defined. Accordingly, bandwidth information isstored in vendor specific attributes permitted for free use by equipmentvendors. It is also possible to include desired parameters in IDs withspecific attributes not assigned.

FIG. 27 shows examples of attributes registered in the RADIUS server.Thereby, the BAS can obtain user bandwidth information during userauthorization.

The BAS performs bandwidth control for the OLT in three ways: first, asshown in FIG. 8, the BAS performs bandwidth control through a systemcontrol interface of the OLT; second, as shown in FIG. 15, the BAS sendscontrol packets to the OLT through a line interface for sending userpackets (hereinafter referred to as in-channel communication) to achieveOLT control; and last, as shown in FIG. 18, the BAS gets the OLT as aline interface of the BAS to directly control the OLT.

Two methods are available to control bandwidths: one method is to changebandwidths allocated to ONUs according to the number of accommodatedusers and user bandwidths; and another method is to control bandwidthsbetween the OLT and ONUs on a user basis. The two bandwidth controlmethods will be described using the drawings for each of systemconfigurations.

Referring to FIG. 8, a description is made of a configuration in whichdownstream bandwidths from the BAS to the OLT are controlled using asystem management interface of the OLT. Protocols required for systemcontrol between the OpS and OLT are defined in ITU-T Q.834.1, and Q3,SNMP (Simple Network Management Program), and CORBA can be used asinterfaces of the OLT. In order that OLT system control is achieved inthe line control unit of the BAS, the line control unit is configured tohave an OLT control interface as shown in FIG. 14. The line control unitcomprises: a physical layer control unit 4001 that physically terminatesuser data; a physical layer control unit 4002 that physically terminatescontrol data; an OLT control unit 4003 that creates packets forcontrolling the OLT; a control interface 4005 that receives controlsignals from the packet processing unit 286 and sends them to the OLTcontrol unit 4003 and a bandwidth control unit 4004; the bandwidthcontrol unit 4004 that controls downstream bandwidths; and a packetprocessing unit interface through which user data is sent and receivedto and from the packet processing unit.

A description is made of a method of changing bandwidths allocated toONUs according to the number of users and bandwidths in theconfiguration of FIG. 8. Although this method performs bandwidth controlon an ONU basis like conventional methods, bandwidths for ONUs arechanged according to the number of users and allocated bandwidths.

FIG. 22 shows control sequences among BAS, OLT, ONU, and users. The BAS28 starts the OLT 10 and then performs initial setting for the OLT 10(901). The BAS 28, during the initial setting (901), allocatesbandwidths to individual ONUs 12 in advance to process control signals.Next, the OLT discovers unregistered ONUs (902). In response, the ONUs12 send a registration request to the OLT 10. The OLT 10 receives theregistration request from the ONUs 12 and makes authorization (903). Ifthe authorization is correctly made, the OLT 10 permits use of a controlbandwidth allocated to the ONUs 12 during the initial setting andnotifies the ONUs 12 of the fact (904). If the ONUs 12 are authorized inthe OLT 10, the user sends an authorization request packet forestablishing PPPoE to the BAS 28 using the control bandwidth permittedin the sequence 904. If PPPoE is correctly established, the userestablishes PPP (906). Upon receipt of the user authorization requestpacket during PPP establishment, the BAS 28 makes a request to theRADIUS server 26 for user information and judges whether to authorizethe user. If authorization information is correct, the BAS 28 obtainsbandwidth information allocated to the user from the user informationand sums the bandwidths of accommodated users for each of the ONUs 12,and then sets bandwidth information of each ONU 12 to the OLT 10 throughthe OpS interface 19 (907). Thereafter, authorization approval is sentto the user and user communication by use of IP is started.

Next, referring to FIG. 23, a detailed description is made of protocolprocessing and settings performed between users and the BAS. The OLT 10,when started (701), performs initial settings of the ONUs (702). In theinitial settings, initial bandwidth setting for the ONUs is performed.Initial bandwidths are used for control to establish PPPoE and PPPbetween users and the BAS; predetermined, fixed bandwidths are set asthe initial bandwidths. Upon termination of the initial settings (702),the OLT discovers unregistered ONUs and performs authorization of theONUs (703). If the authorization is correctly made, the OLT permits useof control bandwidths between OLT and ONUs set in the initial settings(702) (703).

When bandwidths between OLT and ONUs have been allocated in 703, theusers 13 start PPPoE establishment between BAS 28 and users 13 and senda packet for PPPoE establishment to the BAS (705), using the controlbandwidths between OLT and ONU.

When PPPoE has been correctly established between BAS 28 and users 13(706), the users 13 start PPP establishment (707). In the PPPestablishment phase, LCP establishment (708) user authorization (710),and IPCP establishment (714) are performed. These are described in orderbelow. In the PPP establishment phase, LCP (Link Control Protocol) fornegotiation of the data link layer is executed (708). If LCP iscorrectly set (709), user authorization is performed. PAP (PasswordAuthentication Protocol) and CHAP (Challenge Handshake AuthenticationProtocol) can be used as protocols for user authorization; userauthorization is performed using either of the protocols (710). If userauthorization has been correctly performed (711), user bandwidths aresummed on an ONU basis using user bandwidth information obtained fromthe RADIUS server 26 during user authorization (710), and the summationresult is set in the OLT 10 as bandwidths between OLT and ONUs (712).When ONU bandwidths with users in mind have been updated (712), IPCP(Internet Protocol Control Protocol) for performing network settingssuch as user IP setting is established (714). If the PPP establishmentphase is normally terminated, user communication by use of IP is enabled(716).

To realize this method, PON interfaces 106 configured as shown in FIG.10 within the OLT 10 are used to buffer user packets on an ONU basis,whereby bandwidth control is performed. The PON interfaces 106 receiveuser packets from the BAS 28 via the line control unit 100 and theswitch 104. Referring to FIG. 10, a description is made of theconfiguration of the PON interface 106. The PON interface 106 comprises:a switch interface 1062; buffers 1063, 1064; a data distributor 1066; abandwidth control unit 1073; a user buffer 1065; a downstream PONcontrol unit 1067; an upstream PON control unit 1070; an OAM controlunit 1069; a physical layer processing unit 1072; a control interface1061; and a user bandwidth control table 1068. The PON interfaces 106receive data in a switch interface 1062 and buffer user packets in abuffer 1064. A data distributor 1066 distributes the buffered userpackets to ONU buffers 1065 on an ONU basis. A downstream PON controlunit 1067 schedules data reading on the basis of bandwidth informationof each ONU of an ONU bandwidth control table 1068 as shown in FIG. 11,and performs reading from a bandwidth control unit so as to satisfy abandwidth specified for each ONU. The bandwidth control unit 1073outputs packets of a byte count specified by an ONU specified in thedownstream PON control unit 1067. To avoid fragment processing, settingis made to read data every 1500 bytes so that the data is read in apacket unit, and sending from the ONU buffer is terminated when thenumber of remaining sendable bytes becomes less than 1500 bytes.

A description is made of a method of controlling bandwidths between OLTand ONUs on a user basis in the configuration of FIG. 8. In this method,the BAS uses user bandwidth information obtained during userauthorization to set user bandwidths in the OLT, and the OLT outputsuser data on the basis of set user bandwidth information.

In this embodiment, the OLT uses PPPoE session ID 243 as a means foridentifying user packets. A session ID, which is decided for each ofPPPoE sessions, is used by the OLT as key for searching the user controltable used to achieve downstream user bandwidth setting.

Referring to FIG. 24, a description is made of control performed amongBAS, OLT, ONU, and users. Ops of the BAS 28 or OLT 10, after the OLT 10is started, performs initial setting for the OLT (911). Conventional PONsystems set bandwidths at the same time when initial setting isperformed for the OLT. On the other hand, in this embodiment, sincedownstream bandwidths are set based on user information obtained in theBAS, when ONUs are registered, no downstream bandwidths are set and onlyupstream bandwidths are set. When the OLT initial setting terminates(911), the OLT 10 discovers unregistered ONUs (912). In response, theONUs 12 send an authorization request to the OLT (913). Upon terminationof ONU authorization, the users make PPPoE and PPP establishment withthe BAS 28. Referring to FIG. 25, a description is made of PPPoE and PPPestablishment procedures and a downstream bandwidth setting procedure bythe users.

In the PPPoE session 915, PADI (PPPoE Active Discovery Initiation) fordiscovery of BAS to authorize users is sent from the users (9151). Inresponse, the BAS 28 outputs PADO (PPPoE Active Discovery Offer) ofsession ID number 0 (9152). Bandwidth control in the OLT is performed ona session ID basis. Since the session ID number 0 is primarily used forcontrol sequences between users and BAS, a bandwidth used for control isallocated in advance. The first packet PADO (9153) to be sent to theusers 13 from the BAS 28 is also outputted to the ONUs, using thebandwidth (9153). Thereafter, the PADO is read from a user bufferaccording to the bandwidth control table in the downstream PON controlunit 1067, and outputted to the ONUs 12. The ONUs 12 monitor adestination MAC address of the sent Ethernet frame, receive a framedirected to the pertinent ONU, and send the frame to a network 18 underthe ONU. The users 13 receiving the PADO 9152 output PADR (PPPoE ActiveDiscovery) (9154) and make a request to the BAS 28 for a session ID forsession establishment. Upon receipt of it, the BAS 28 issues a PPPoEsession ID, registers it in the OLT, and temporarily registers apredetermined control bandwidth (9155). Then, the BAS 28 outputs PADS(PPPoE Active Discovery Session Confirmation) for assigning a PPPoEsession ID to the users 13, using a session ID uniquely assigned to auser session to the OLT (9156). Upon receipt of the PADS from BAS, theOLT checks the session ID, outputs the PADS to the ONUs in the bandwidthfor control set by the BAS (9157), and completes PPPoE establishment.The users recognize the session ID assigned to them by receiving thePADS (9157), and use the session ID from the next output to performcommunications. Since the session ID corresponding to the users 13 hasbeen registered in the OLT 10, subsequent communications between the BASand the users can be performed using the session ID. The completion ofPPPoE establishment is followed by PPP establishment (916). In PPP,first, LCP (Link Control Protocol) is executed (9161) and negotiation ofthe data link layer is conducted. Next, user authorization is conducted.Although, in PPP, PAP (Password Authentication Protocol) and CHAP(Challenge Handshake Authentication Protocol) can be used as userauthentication procedures, only PAP is described here. In the PAP, foran authentication request (9162) from the users, a user ID and passwordare sent. Upon receipt of them, the BAS uses the RADIUS server to checkthe user ID and password (9163). If they are correct, the BAS formallyregisters a downstream bandwidth in the OLT, using user informationobtained at the same time as authorization (9164). After the formalregistration, the BAS sends Authentication-Ack to the users (9165) andterminates the authorization. If the authorization fails,Authentication-Nak is sent to the users and the session ID set in theOLT is discarded. In this case, if the users are to try registrationagain, they must begin from the establishment of PPPoE session. If theauthorization has been correctly made, the setting of networks of theusers is performed using IPCP (Internet Protocol Control Protocol) andthe users start communication.

Referring to FIG. 26, a detailed description is made of protocolprocessing and settings performed by the BAS. After the OLT 10 isstarted, the BAS 28 performs initial setting for the OLT (802). In theinitial setting, upstream bandwidths are set for the ONUs. Downstreambandwidths are set when PPP has been established and user authorizationhas been correctly made. At the termination of the initial setting, theOLT discovers ONUs and authorizes unregistered ONUs, and allocatesupstream bandwidths (803). If ONU authorization is correctly made, theusers 13 send a packet for establishing PPPoE to the BAS (804). Althoughdownstream bandwidths are not yet set, for a session ID number 0 used toestablish PPPoE, a bandwidth for control is allocated in advance duringthe initial setting. If a PPPoE session ID is decided for the users, thesession ID is registered in the OLT. The bandwidth at this time isdefined as a bandwidth for control. If PPPoE is correctly establishedbetween the BAS 28 and users 13 (806), the users 13 start PPPestablishment (808). In the PPP establishment phase, LCP establishment(809), user authorization (811), and IPCP establishment (812) areperformed. These are described in order below. In the PPP establishmentphase, LCP (Link Control Protocol) for negotiation of the data linklayer is executed (809). If LCP is correctly set (810), userauthorization is performed. PAP (Password Authentication Protocol) andCHAP (Challenge Handshake Authentication Protocol) can be used asprotocols for user authorization; user authorization is performed usingeither of the protocols (811). If user authorization has been correctlyperformed (812), user bandwidth information obtained from the RADIUSserver 26 during user authorization (811) is set in the bandwidthcontrol table 1068 of the OLT (813). Upon completion of the userauthorization (812), IPCP (Internet Protocol Control Protocol) forperforming network settings such as user IP setting is executed (814).If the PPP establishment phase is normally terminated, usercommunication by use of IP is enabled (817).

Referring to FIG. 12, a description is made of the configuration of thePON interface 106 in the case where the above-described method is used.The PON interface 106 comprises: a switch interface 1062; a buffer 1064;a data distributor 1166; a bandwidth control unit 1073; a user buffer1165; a downstream PON control unit 1067; an upstream PON control unit1070; an OAM control unit 1067; a physical layer processing unit 1072; acontrol interface 1061; and a user bandwidth control table 1168.

On correctly authorizing users, the BAS 28 sets a user bandwidth basedon user bandwidth information in the OLT 10 via the OpS interface. Thebandwidth setting information sent from the OpS interface of the BAS orOpS of the OLT terminates in the OpS interface of the OLT and is sent tothe control interface 1061 of the PON interface 106 via the systemcontrol unit. Upon receipt of the bandwidth setting information, thecontrol interface 1061 writes a user session ID and a bandwidth to beset to the user bandwidth control table 1068 as shown in FIG. 13. Adescription is made of processing of upstream packets received fromusers in the PON interface 106. Upon receipt of PPPoE packets sent fromthe users, the PON interface 106 terminates the physical layer in thephysical layer processing unit 1072 and sends them to the upstream PONcontrol unit 1070. The upstream PON control unit 1070 separatesadditional headers appended to OAM packets and user data from the OAMpackets and the user data. The separated user data is sent to a buffer1063 and sent to a switch through the switch interface 1062. The OAMpackets separated in the upstream PON control unit 1070 are sent to anOAM control unit 1069 and system control information is sent to thedownstream PON control unit 1067.

A description is made of processing of downstream packets received fromthe BAS 28 in the PON interface 106. Upon receipt of PPPoE packets sentfrom the BAS 28, the PON interface 106 stores data in the buffer 1063via the switch interface 1062. The data distributor distributes packetsin the buffer by session ID and stocks them in user buffers managed bysession ID. The downstream PON control unit 1067 schedules data readingon the basis of information of a user bandwidth control table 1068, andgives directions to a bandwidth control unit so as to satisfy abandwidth specified for each user (session ID). The bandwidth controlunit 1166 outputs packets of a byte count specified by a session IDsupplied from the downstream PON control unit 1173. To avoid fragmentprocessing, setting is made to read data every 1500 bytes so that thedata is read in a packet unit, and sending from the session ID isterminated when the number of remaining sendable bytes becomes less than1500 bytes.

The downstream PON control unit 1067 reads downstream bandwidthinformation from the user bandwidth control table 1168 and reads datafrom the user buffers according to bandwidth information. Also,according to requests from the OAM control unit 1069, the downstream PONcontrol unit 1067 inserts OAM packets or sends system control packets.Until the BAS recognizes users and a PPPoE session is established, aPPPoE session ID of 0 is used. Accordingly, this method reserves the ID0 as ID for system control and allocates a predetermined bandwidth to itin advance.

A description is made of a configuration in FIG. 15 in which OLT controlis achieved by in-channel communication from the BAS. This methodprovides no special interface for OLT control and multiplexes userpacket and control packets on identical physical lines. In FIG. 8, aspecial physical line is used to transfer control packets, while, inFIG. 15, a physical line used to transfer control packets is the sameline used to transfer user packets. The BAS and the OLT operate in thesame way as in FIG. 8. In FIG. 15, the BAS multiplexes control packetson user packets, and the OLT separates the control packets from the userpackets. To achieve this function, a control data separation unit isadded to the OLT to send control data to the system control unit.Functional blocks of the BAS are shown in FIG. 16 and functional blocksof the OLT are shown in FIG. 17. A flow of control data is describedbelow.

The BAS 33 sends control packets to the OLT 35 through a line interface34 like normal user packets. PPPoE session IDs exclusively used forsystem control are assigned to the control packets to distinguish themfrom user packets and set in PPPoE headers. The control packets areinputted to the line control unit 100 together with user packets andinputted to a user data/control data separation unit 103. The userdata/control data separation unit 103 monitors PPPoE session IDs ofinputted packets, and on detecting PPPoE session IDs assigned forcontrol, sends the control packets to the system control unit 102 of theOLT. The system control unit 102 sets user bandwidths and performssystem settings on the basis of the data of the control packets. Theconfiguration of FIG. 15 allows two bandwidth control methods as theconfiguration of FIG. 8 does because the former is different from thelatter only in means for controlling the OLT.

Next, a configuration in which the BAS and the OLT are integrated isdescribed referring to FIG. 18. In this configuration, a functioncorresponding to PON interfaces of the OLT is accommodated as a lineinterface of the BAS. OLT interfaces 361 are connected to packetprocessing units 332 of the BAS 36, and directly control microcomputerbuses 312 of the packet processing units. However, control linescontrolling the line interfaces are not limited to microcomputerinterfaces because they depend on the configuration of the packetprocessing units. Procedures for user authorization and downstreambandwidth setting are the same as in the configuration of FIG. 8, exceptfor a procedure for controlling a unit corresponding to the OLT and theinstallation of OLT interfaces instead of PON interfaces. Referring toFIGS. 19 and 20, a description is made of a procedure for setting userbandwidths in the OLT by use of microcomputer buses.

FIG. 19 is a functional block diagram of the BAS integrated with the OLTwherein the OLT interfaces 361 are installed in the BAS 36. The OLTinterfaces are different from the PON interfaces installed in the OLT inthat the former includes a CPU interface 3612 corresponding to themicrocomputer interfaces serving as control lines from the packetprocessing units, and an internal interface 3611 through which data issent and received to and from the packet processing units. In caseswhere settings for the line control unit of the OLT interfaces 361 areperformed from the OpS of the BAS, the BAS performs the settings throughthe packet processing unit directly connected with the line controlunit. System control information of the OLT interfaces 361 received inthe OpS Interface 282 of the BAS 36 is inputted to the system controlunit 281 and outputted to the microcomputer buses. System controlinformation outputted to the microcomputer buses is transferred to theCPU interface of the OLT interfaces 361 via the packet processing units332. The CPU interface 3612 transfers the received system controlinformation to the OLT interfaces and performs settings for individualblocks. Also, settings for the OLT interfaces from the packet processingunits 332 are performed in the same way using the microcomputer buses ofthe packet processing units.

FIG. 21 is a functional block diagram of the packet processing units286. The packet processing units each comprise: a switch interface 286-2that sends user data to the switch; a packet processing engine 286-3that includes a microprocessor to perform protocol processing for userpackets and decide output paths; a line control unit interface 286-4that performs conversion between a system control bus 289 within the BASand the microcomputer buses 312 of the packet processing units 333; anda system control unit interface 286-1 that performs conversion betweenthe system control bus 289 within the BAS and the microcomputer buses312 of the packet processing units and transfers control informationfrom the system control unit 281 of the BAS to the packet processingunits. The direct connection of the control bus 312 of the OLTinterfaces 361 to the microcomputer buses enables settings from the OpSand the packet processing engine.

In the configuration of FIG. 18, bandwidth control can be performed bythe above-described two methods.

The present invention enables bandwidth control over users under theONUs. With bandwidth control on an ONU basis, appropriate bandwidths canbe allocated by summing the bandwidths of users accommodated in each ONUon the basis of the number of users and user bandwidths obtained by BASuser authorization. With bandwidth control on a user basis, bandwidthsassigned to users under ONUs can be allocated.

1. A packet communicating system comprising: an optical line termination(OLT) for subsidiarily connecting optical network units (ONUs) by thePassive Optical Network type (PON), said OLT having a function forterminating the physical layer of the PON and controlling bandwidths inphysical lines between the OLT and the ONUs; and a broadband accessserver (BAS) connected to said OLT, said BAS having a function forauthorizing users communicating with the Internet, via the ONUs and theOLT, wherein said BAS has a function for controlling said OLT through afirst physical line connecting therefrom and directly to the OLT, usinginformation of the users obtained from only one Remote AuthenticationDial In User Service (RADIUS) server which is connected only with theBAS and manages information of the users when authorizing the users tocommunicate with the Internet, and the BAS has a function for sendingand receiving bandwidth control packets through said first physical lineto the OLT for controlling user bandwidths at the OLT, and settingbandwidths per user for the users to send and receive user packetsthrough a second physical line directly connecting between the BAS andthe OLT.
 2. A packet communicating system comprising: an optical linetermination (OLT) for subsidiarily connecting optical network units(ONUs) by the Passive Optical Network system (PON), said OLT having afunction for terminating the physical layer of the PON and controllingbandwidths in physical lines between the OLT and the ONUs; and abroadband access server (BAS) connected to said OLT, said BAS having afunction for authorizing users communicating with the Internet via theONUs and the OLT, wherein said BAS has a function for controlling saidOLT by sending and receiving bandwidth control packets between the BASand the OLT through a first physical line directly connecting betweenthe BAS and the OLT to transfer user packets exchanged between theInternet and the users via a second physical line directly connectingbetween the BAS and the OLT, using information of the users obtainedfrom only one Remote Authentication Dial In User Service (RADIUS) serverwhich is connected only with the BAS and manages said information of theusers when authorizing the users to communicate with the Internet, andsaid bandwidth control packets control user bandwidths at the OLT bysetting bandwidths per user for the users to send and receive said userpackets.
 3. The packet communicating system according to claim 1,wherein said packet communicating system having a function forcontrolling bandwidths for the users to send and receive packets,allocated between the ONUs and the OLT, according to the number of usersaccommodated under the ONUs or bandwidths allocated to the individualusers.
 4. The packet communicating system according to claim 1, whereinsaid packet communicating system having a function for controllingbandwidths for the users to receive packets between the OLT and the ONUsfor each of users accommodated under the ONUs.
 5. The packetcommunicating system according to claim 2, wherein said packetcommunicating system having a function for controlling bandwidths forthe users to send and receive packets, allocated between the ONUs andthe OLT, according to the number of users accommodated under the ONUsand bandwidths allocated to the individual users.
 6. The packetcommunicating system according to claim 2, wherein said packetcommunicating system having a function for controlling bandwidths forthe users to receive packets between the OLT and the ONUs for each ofusers accommodated under the ONUs.
 7. A packet communicating systemcomprising: a plurality of optical network units; a star couplerconnected with the plural optical network units; and a packetcommunicating apparatus connected with the star coupler, wherein thepacket communicating apparatus multiplexes sending data to the pluraloptical network units and sends the multiplexed sending data to the starcoupler, the star coupler broadcasts the multiplexed sending data to theoptical network units, and each of the optical network units receivesdata directed thereto, wherein the packet communicating apparatuscomprises: an optical line termination (OLT) for subsidiarily connectingoptical network units (ONUs) by the Passive Optical Network system(PON), said OLT having a function for controlling bandwidths between theoptical line termination and the optical network units; and a broadbandaccess server (BAS) connected to the optical line termination, that hasa function for authorizing users who communicate with a network via theoptical network units and the optical line termination, wherein the BAShas a function for controlling said OLT by sending and receivingbandwidth control packets between the BAS and the OLT through a firstphysical line directly connecting between the BAS and the OLT totransfer user packets exchanged between the Internet and the users via asecond physical line directly connecting between the BAS and the OLT,and using information of the users obtained from only one RemoteAuthentication Dial In User Service (RADIUS) server which is connectedonly with the BAS and manages said information of the users whenauthorizing the users to communicate with the Internet, and saidbandwidth control packets control user bandwidths at the optical linetermination by setting bandwidths on a per-user basis for the users tosend and receive said user packets.